A field experiment was conducted on sandy loam soil at Hisar, India during the autumn seasons 1984–85 and 1985–86 to study root characters, evapotranspiration, water use efficiency, moisture extraction pattern and plant water relations of rape genotypes under varying irrigation schedules. Root volume and dry weight increased, while tap root and lateral root lengths decreased with irrigation. Increased irrigation frequency increased evapotranspiration but decreased water use efficiency. The relative water content and osmotic potential of the leaves increased with more frequent irrigation, but plant water retention capacity decreased. There were genotypic differences between the characters examined. © 1990, Cambridge University Press. All rights reserved.